The present invention relates to a manually guided implement, such as power chain saws, brush cutters and the like, having an air-cooled internal combustion engine for driving a tool. The engine is disposed within an implement housing, and a fan wheel is provided that is fixedly held on a crankshaft of the internal combustion engine and is accommodated in a cooling air spiral case that is open toward the engine. Formed in the implement housing is an air inlet through which ambient air can be drawn into the cooling air spiral case and can be conveyed to the internal combustion engine.
With heretofore known implements, the tool is driven by an internal combustion engine that is disposed within an implement housing. To convey the cooling air for the internal combustion engine, a fan wheel is provided that is fixedly held on a crankshaft of the internal combustion engine and rotates in a cooling air spiral case that is open toward the internal combustion engine.
DE 197 52 798 A1 discloses an implement according to which, during operation of the engine, the rotating fan wheel draws in ambient air through a fan cover into the cooling air spiral case in the implement housing. From the cooling air spiral case the cooling air stream passes to the cylinder of the internal combustion engine and is discharged from the implement housing via outlet slots. An opening is provided in the base of the cooling air spiral case and an air for combustion channel to an air filter of the engine is connected to the opening. In this way, a partial stream is branched off from the cooling air stream and is conveyed as air for combustion to the internal combustion engine.
DE 196 18 669 A1 discloses a manually guided implement having an air for combustion inlet opening disposed in the base of the cooling air spiral case, whereby air for combustion is conveyed out of the interior of the implement housing through the inlet opening, and is conveyed to the engine in an air for combustion channel that follows in the direction of flow.
With manually guided implements, the implement housing is to be small and compact, as a result of which increased temperatures can occur in the compact internal combustion engine. Especially when four-stroke engines are utilized in the housings of implements, considerably higher temperatures result despite external air cooling.
It is therefore an object of the present invention to further develop an implement of the aforementioned general type in such a way that the cooling of the internal combustion engine is improved.